Thermostat for ice chests



March 19, 1957 E. P. MASSON 2,736,115

THERMOSTAT FOR ICE CHESTS 'Filed May 18, 1954 INVENTOR: EMILE PIERREMAssON,

HIS A6EN7'5.

My invention has for its object a thermostat for ice chests,characterized by its great simplicity and its high sensitivity, wherebyit is far superior to the thermostats generally used for ice chests.This thermostat is designed on the principle of the expansion of waterwhen freezing inside a yielding casing for a suitable cross-section.

It may be noticed as a matter of fact that, for the applicationconsidered, it is sufficient to adjust the temperature to a value nearfreezing point at a suitably selected point inside of the chest and,under such conditions, it seems to be of advantage to benefit by thesudden increase in volume when water is freezing. If it is preferred toselect a slightly different temperature for adjustment purposes, it ispossible to adjust the temperature of freezing by incorporating a smallamount of a suitable liquid such as alcohol or glycerin.

On the other hand, it is possible, with such a thermostat, to modifywithin certain limits the temperature of adjustment either by shiftingthe thermostat inside the ice chest or else by inserting heat-insulatingscreens adapted to make said chest assume according to the case atemperature nearer that of the walls or that of the evaporator.

I will now describe by way of example, reference being made toaccompanying drawings, a simple embodiment of my improved thermostat;its small size allows it to be easily housed inside all ice chests. Insaid drawrngs:

Fig. 1 is an elevational partly sectional view of the thermostat;

Fig. 2 is a cross section through line AB of Fig. 1;

Fig. 3 is a plan view thereof.

In the example illustrated, I resort to a metal tube 1 having an ovalcross-section such as that of the tubes used in manometers, folded intoU-shape and almost entirely filled with water. The two ends of the tubeare fiat and closed by welding, as apparent at 1a. Metal blades 2 aresecured to said ends and carry contact-pieces 4 which are insulated bymeans of sleeves and washers 3 made of insulating material. Thesecontact-pieces cooperate in the clamping of insulated yielding wires 5to provide connection between the latter and the contactpieces.

The contact-pieces are adjusted in a manner such that they engage eachother when at room temperature and that their separation is producedonly when the U-shaped tube opens and its arms are spaced by 2 to 3 mm.With a tube of the type illustrated which may assume a height of 70 mm.and a breadth of 60 mm. with an oval crosssection the major axis ofwhich has a length of about 15 mm., the transformation of all the watercontained therein into ice opens the arms of the U by about 6 to 8 mm.The separation is thus already performed when only part of the water hasfrozen. The adjustment is executed once and for all and provides a largesafety margin which takes into account slight fortuitous deformationsand the nited States Patent ice possibility of a wear of the contactpieces. The sole modification which may appear lies in the fact thatwhen first starting the operation of the ice chest after a stoppage, thetime required for the contact pieces to open is not constant; but allthe following movements of the thermostat will be executed to eitherside of the new position of equilibrium thus defined. The system maythus be considered as proof against misadjustment. On the other hand,the stresses relied on are of the magnitude of a few hundred grams,which allows resorting to tungsten contact-pieces the wear of which issmall and it is unnecessary to resort to special steps for ensuring asudden opening. Lastly, the transmission of heat to the water through ametal tube and also the small size of the arrangement ensures a very lowcalorific inertia.

With a view to protecting the thermostat against shocks or fortuitouscontacts, it is of advantage to locate it in side a small metal casing,perforated or otherwise, while leaving a suflicient clearance withreference to the latter so as to allow the U to open to a maximum; onlythe insulated wires pass out of the casing. The U-shaped tube may beheld in position by very weak springs which prevent it from assuming anabnormal position or from being shaken during transportation. Sucharrangements are easy to provide and require no special description.

An advantage of the embodiment disclosed resides in that if, for anyreason whatever, the tube has been insufiiciently filled with water, itis easy to flatten it over a small further length so as to reduce itsfree volume to the desired value. Furthermore, the temperature at whichthe filling has been performed is not critical since the effects ofexpansion of water are negligible as compared to those arising throughthe formation of ice.

As already mentioned, it is possible to execute a thermostat for atemperature different from normal freezing point by incorporating to thewater glycerin, alcohol or the like.

It is also possible, as disclosed, to modify the temperature ofoperation of the ice chest by shifting the thermostat inside the latteror by inserting heat-insulating screens in front of said thermostat.This may be performed in any suitable manner and no further descriptionis required for such arrangements.

It should be remarked that the thermostat being at a temperature higherthan that of the evaporator, there is no condensation of water to befeared, which condensation would be detrimental to its proper operation.

The direct action of the U-shaped tube on the contactpieces has beendisclosed as the simplest embodiment of my invention, but it will bereadily ascertained that by reason of the large movement obtained forthe ends of the U-shaped tube, the deformations of the U may betransmitted mechanically outside the chest, for instance through ayielding cable.

What I claim is:

l. A thermostat, for use in controlling the electric switching mechanismof a refrigerator including two switch contacts, comprising incombination, a narrow hollow closed metallic tube filled with a body ofwater and disposed on the interior of said refrigerator, said tube beingbent and carrying on one end portion one of said contacts, the othercontact being mounted with relation to the second end of said tube, saidfirst end being movable relative to said second end in response totemperature changes prevailing internally of said refrigerator near saidtube causing changes of the volume of the body of water inside said tubethereby deforming said tube, whereby said contacts will within a certaintemperature range be interengaged and within an other temperature rangebe disengaged.

2. A thermostat, for use in making and breaking an a electric circuit inresponse to temperature changes, comprising a closed hollow elongatedtube bent to have its ends in a first position spaced apart for apredetermined distance, a body of liquid expanding upon freezing andcontracting upon unfreezing disposed on the interior of said tubeforcing one end to move relative to the other into a second position ofincreasing distance between said ends upon freezing of said liquid, saidtube being operable to return said ends to said rest position uponunfreezing of said liquid, two contacts for said circuit, one contactbeing connected to an end of said tube, said contacts being operable tobe interengaged in one of said positions and to be disengaged in theother position.

3. A thermostat, for use in making and breaking between two contacts anelectric circuit in response to temperature changes, comprising incombination, a closed hollow U-shaped tube, one of said contacts beingconnected with relation to each end of said tube, one of the ends ofsaid tube being movable relative to the other between a first positionwherein said contacts are interengaged and, respectively, a secondposition wherein said contacts are spaced from each otherout-of-engagernent, a body of substance disposed in the interior of saidtube having the properties to be liquid above a certain temperature andto be frozen below that temperature and to expand upon freezing and,respectively, to contract upon unfreezing forcing upon expansiongenerated by freezing the ends of the tube from the first position tothe second position, said tube being operable to return said ends uponunfreezing of said substance from the second position to the firstposition.

4. An element, for use in connection with the interengagement anddisengagement of two electric contacts for making and breaking anelectric circuit, comprising a closed hollow U-shaped tube, the ends ofsaid tube being connected with relation to said contacts and beingmovable relative to each other between a first position of spacing apartfrom each other of said ends and, respectively, a second position ofspacing apart of said ends for a distance different from that of saidfirst position, a liquid substance disposed on the interior of saidtube, said liquid substance having the properties to expand uponfreezing and to contract upon unfreezing and forcing upon freezing theends of the tube from the first position to the second position, saidtube being operable to return said ends upon unfreezing of saidsubstance from the second to the first position.

References Cited in the file of this patent UNITED STATES PATENTS Re18,154 Hull Aug. 18, 1931 1,475,313 Newhard Nov. 27, 1923 2,187,258 WoodJan. 16, 1940 2,453,851 Miller Nov. 16, 1948 2,622,923 Cobb Dec. 23,1952

